Sunlight, heat and humidity weaken coronavirus: US official

The coronavirus appears to weaken more quickly when exposed to sunlight, heat and humidity, a US official has said, in a potential sign that the pandemic could become less contagious in summer months.

US government researchers have determined that the virus survives best indoors and in dry conditions, and loses potency when temperatures and humidity rise - and especially when it is exposed to sunlight, said William Bryan, acting head of the US Department of Homeland Security's Science and Technology Directorate.

"The virus dies quickest in the presence of direct sunlight," he told a White House news briefing.

However, the virus proven lethal in several countries with warm climates, raising questions about how much impact seasonal change in the US will have.